For the last 30 years or so, one common mounting assembly for vehicle interior rearview mirrors has been a tubular dual ball and spring construction such as disclosed by U.S. Pat. No. 3,367,616 Bousch et al. With that construction, a spring biases vehicle-mounted and mirror-mounted balls into engagement with opposite ends of a tube, and the mirror can be adjusted by rotation of each of the two balls. It is usually desirable to adjust the mirror at the mirror-mounted ball; however the same spring biases both balls and as such both will rotate at the same level of force unless there are different clamp members or ball clamp members of the same construction but made of materials having different coefficients of friction. Other dual ball mounts of this type are disclosed by U.S. Pat. Nos. 4,646,210 Skogler et al., 5,327,288 Wellington et al., and 5,521,760 DeYoung et al.
Vehicle interior rearview mirrors of the automatic dimming type are conventionally about twice as heavy as standard rearview mirrors and, as such, it is desirable for the mirror ball to be located closer to the center of gravity of the mirror in order to facilitate its adjustment. See, U.S. Pat. No. 5,572,354 Desmond et al. which has a three ball mount wherein two balls are located within a tube with one adjacent the vehicle and the other adjacent the mirror and with the mirror ball having a third ball that is received by a mirror housing socket to provide mounting thereof. Thus, this mounting assembly has three locations of rotatable adjustment as opposed to the two locations of adjustment with a dual ball type of mounting assembly as described above.
Vehicle interior rearview mirrors have also previously included ball connections having balls with holes through which electrical wires can pass such as disclosed by U.S. Pat. Nos. 2,414,223 DeVirgilis and 5,308,247 Dyrdek.
Other vehicle interior rearview mirrors are disclosed by U.S. Pat. Nos. 4,614,412 Cohen and 4,822,140 Mittelhauser.